More than 50 families who already knew their homes had been swept away by Sunday's fierce firestorm were allowed to return to the charred ruins for the first time today.

For hundreds of others, however, the extent of the damage is still unknown, as they prepare to return to the cold reality of what authorities are calling the "warm zone".

Brian and Margaret Griffin, Hills residents for 14 years, saw flames lapping at their generator shed before they left.

They are hopeful their home has been spared.

"We just saw the smoke and the helitac going around and less than 20 minutes later we saw the flames, so we got out," Ms Griffin said.

"We were right on the edge."

The Griffins, like scores of others, queued for permits that would allow them to return to their homes through the continuing roadblocks and hoped to assess the damage later today.

Garry Elwood searches for valuables in his Narla Retreat home. Picture: Michael O'Brien/The West Australian

Neighbour Jason Gauchi was also in the dark, and living in hope.

He and his family, including children aged 20 months and three months, were planning to move into their dream Hills home next week.

"It was just going to be a complete change in the lifestyle - now it is just a lot of unknowns," he said.

Colin and Sue Daniels have lived in the Perth Hills for 28 years, and were sure their home had been destroyed.

But no news from the Mundaring Shire - which contacted all those whose properties had been destroyed - was extremely good news.

"On the video flyover (taken from a fire authority helicopter), I think I saw the roof of our house and it looks in one piece," Mr Daniels said.

He admitted his personal relief was mixed with guilt.

But Ms Delich said those who were lucky should not feel guilty.

"It's bad luck and that's all it is," she said.

"We live in the bush and we know it can happen, and unfortunately it happened to us."

Counselling services are available to the people confronted with the reality of their loss.

"To be told verbally is one thing, to see it visually is quite another," Deputy Fire Commissioner Brad Stringer said.

The loss was mixed with growing frustration for other residents, who were asked to prove their address before being given a permit to be allowed to return to their homes to assess the damage.

Fire Commissioner Wayne Gregson, a Hills resident himself, said he could understand the heightened emotion.

"I accept that as a potential possibility, some people will say bugger the authorities and go back in," Mr Gregson said.

"They are putting themselves at risk by ignoring the roadblocks, but I can understand that - if it was my house I'd be equally as anxious to know."

Nearly a dozen people were forced to sleep at an emergency evacuation centre set up in nearby Swan View, with dozens more displaced families relying on the goodwill of friends and family.

The generosity of locals had been so overwhelming with donations of clothes, toys, blankets, and personal items that people have been asked to use a local Salvation Army depot to drop off donations, or donate money to a disaster fund instead.

The fire is being blamed for the death of one man, 62-year-old Ron Shaw, who collapsed as he stood on the roof of his Hovea home to prepare for the flames.

Insurance assessors started reviewing claims in the bushfire-affected communities, with more than 300 claims topping $13 million.

Power remained out for about 450 homes late today.

As the emergency response gave way to investigation, Mr Gregson confirmed the fire was most likely sparked by a fallen power pole on a private property, which remains the responsibility of the homeowner to maintain.

Thousands of private power poles are spread across the State, and have already been blamed for sparking a bushfire last January that threatened houses in Chidlow.